Process of obtaining pure caoutchouc, gutta-percha, and the like.



UNITED STATES PATENT OFFICE.

HEINRICH SGHOLZ, 0F BERLIN, GERMANY, ASSIGNOR, BY MESNE ASSIGNMENTS, TO THE FIRM OF KAUTSCHUKGESELLSGHAFT SCHCN & COMPANY, OF HARBURG-ON-THE-ELBE,

GERMANY.

PROCESS OF OBTAINING PURE CAOUTGHOUC, GUTTA-IPEROHA, AND THE LIKE.

Specification of Letters Patent.

Patented June 8, 1909.

Applicationfiled February 27, 1906. Serial No. 308,215.

resinous materials as by-products.

The essential feature of the invention is, that the raw material "(especially such .as hitherto could not be purlfied by washing on account of the large percentage of resin or for other reasons) is either directly or after 'the usual first cleaning (and if necessary after comminution) treated with anilin, a

noninflammable material, or equivalent al ble part. The latter consists of pure caoutchouc, while in the solution are found the resinous oily and waxy ingredients of the raw material, and if the latter should contain gutta percha, this also is found therein. The gutta percha can be separated from the solution by cooling the latter, or by a precipitant (such as water, alcohols, acetone, etc.) and the resins can be separated from the anilin by distillation by means of steam or the like.

I will now proceed to give some practical examples of the manner in which. the process can be carried out.

Example 1: 10 kilograms of one of the poor quality gums of commerce are boiled for some two hours with 15 kilograms of anilin with the addition of 5 kilograms of water as for instance of a reflux-cooler. After boiling, the residue is separated (if desired, by pressure) from the solution in wellknown manner, and is then washed and dried. The solution, as above described, is then submitted to steam distillation, whereby the resins remain' behind, the anilin passing over with the steam. A secondary advanta e of adding'water is that salts, vegetable uices, etc. are washed out of the raw material, such as would not be removed by the resin solvents.

Example 2: To 10 kilograms of the highly resinous raw material known in the trade as Flakes, Accra Paste, Euphort-ia, or "Almeidinaj which hitherto could only be worked by melting, 20 kilograms of anilin are added and the whole boiled for some two hours in the reflux-cooler. Care must be taken that the temperature does not rise to or near the melting point of the rubber. For

this reason it is of advantage either to work with a water-bath, or to add-to theanilin such liquids of low boiling point as do not dissolve caoutchouc, which act" as precipitants, and do not allow the temperature to rise above the desired limit. For this purpose the rubber precipitants (water, alcohols,

acetone etc.) are particularly suitable. After i boiling, the residue from the solution is' separated 1n the manner descrlbed under Example 1, and the anilin separated by steam distillation from the resins and thus recovered. kylized products, the soluble part with the 25 solvent being then separated from the insolu- Example 3: 10 kilograms of New Guinea raw guttapercha, hitherto of little value on account of the large percentage of resin contained, are treated with 25. kilograms of anilin at a suitable temperature, as in the preceding example. From the solution obtained the gutta is separated by intense coolings or bydhe addition of one or more of thealready mentioned precipitants, while the resinous and waxy ingredients re main in solution. From the latter the precipitants are first removed (unless water has been employed as such) in well-known manner by distillation, and the resin remaining in the anilin then separated by steam distillation. ()r the precipitant may be added to the anilin at the commencement and boiled therewith.

Example 4': 10 kilograms of'washed raw rubber containing an average, or high percentage of resin, such, for instance, as Madagascar, are boiled for say an hour with 10 kilograms of anilin and-10 kilograms of water, in the place of which other precipitants may be used. The varioussubstances are separated from each other as in the above cited examples.

tion. since the resins, at the vulcanizing temperature, melting, take up sulfur, causing a disturbing reaction in the rubber, and sinter and seriously affect the homogeneity of the material.

Vvliat I do claim as my invention and desire to secure by Letters Patent, is-

1. The process of obtaining pure caoutchoue and gutta from crude rubber gums and the like containing resin, which consists in dissolving the resin with anilin, or its alkyl-ized substitution products, while maintaining the temperature below the melting point of rubber, and then separating the pure. caoutchouc and gutta from the solution.

2. The rocess of obtaining pure caoutchouc and gutta from crude rubber gums and the like, containing resin; which consists in dissolving the resin with anilin or its alkylized substitution to the anilin, an indi erent agent for the purpose of keeping down the temiernhu'e. and then separating the pure caoutcl iouc and gutta from the'solution.

roducts, and adding In testimony whereof I have tllllxttl my 25 

